Associated with any piece of equipment having an enclosure for containing a fluid is the possibility of localized damage in the wall of the enclosure that may result in leaking of the fluid from the enclosure. For instance, pipes and pressure vessels often contain gaseous fluid under pressure. If the wall of the pipe or pressure vessel is subject to localized damage, e.g., in the form of a small hole or pinhole, mechanical clamps are known for use as a temporary repair. FIG. 1 illustrates one such known mechanical clamp 10, also referred to interchangeably as a bolted box, a mechanical seal, a leak seal and a mechanical enclosure, as installed on a vessel wall 1. The mechanical clamp 10 shown includes a plate held in place with retainer rods and an injection valve through which sealant is applied to the vessel wall 1 in the vicinity of a leak. Such repairs are often excessively heavy as to be impractical. As can be seen from FIG. 1, internal pressure from within the enclosure tends to apply force on the repair which tends to separate the repair from the vessel and weaken the repair over time. Thus, a supplemental “strong back” device may be necessary to hold the repair in place. A superior solution as compared to the use of a strong back device can be welding the repair in place. However, welded repairs have as a disadvantage that post welding heat treatment (PWHT) of the enclosure wall is also frequently required, particularly in harsh process conditions, to decrease the risk of material degradation such as stress corrosion cracking. This heat treatment results in significant added associated time and expense and in some cases is impractical. Compounding the problem is the fact that the localized damage in the pipe or vessel wall is often in a very inconvenient location.
There exists a need for an alternative to the known vessel wall repair methods that would be more cost and time effective while still ensuring safety and reliability.